#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <uv.h>

uv_loop_t* loop;
uv_pipe_t queue;

typedef struct {
  uv_write_t req;
  uv_buf_t buf;
} write_req_t;

void free_write_req(uv_write_t* req) {
  write_req_t* wr = (write_req_t*)req;
  free(wr->buf.base);
  free(wr);
}

void alloc_buffer(uv_handle_t* handle, size_t suggested_size, uv_buf_t* buf) {
  (void)handle;
  buf->base = malloc(suggested_size);
  buf->len = suggested_size;
}

void echo_write(uv_write_t* req, int status) {
  if (status) {
    fprintf(stderr, "Write error %s\n", uv_err_name(status));
  }
  free_write_req(req);
}

void echo_read(uv_stream_t* client, ssize_t nread, const uv_buf_t* buf) {
  if (nread > 0) {
    write_req_t* req = (write_req_t*)malloc(sizeof(write_req_t));
    req->buf = uv_buf_init(buf->base, nread);
    uv_write((uv_write_t*)req, client, &req->buf, 1, echo_write);
    return;
  }

  if (nread < 0) {
    if (nread != UV_EOF)
      fprintf(stderr, "Read error %s\n", uv_err_name(nread));
    uv_close((uv_handle_t*)client, NULL);
  }

  free(buf->base);
}

void on_new_connection(uv_stream_t* q, ssize_t nread, const uv_buf_t* buf) {
  (void)buf;
  if (nread < 0) {
    if (nread != UV_EOF)
      fprintf(stderr, "Read error %s\n", uv_err_name(nread));
    uv_close((uv_handle_t*)q, NULL);
    return;
  }

  uv_pipe_t* pipe = (uv_pipe_t*)q;
  if (!uv_pipe_pending_count(pipe)) {
    fprintf(stderr, "No pending count\n");
    return;
  }

  uv_handle_type pending = uv_pipe_pending_type(pipe);
  assert(pending == UV_TCP);

  uv_tcp_t* client = (uv_tcp_t*)malloc(sizeof(uv_tcp_t));
  uv_tcp_init(loop, client);
  if (uv_accept(q, (uv_stream_t*)client) == 0) {
    uv_os_fd_t fd;
    uv_fileno((const uv_handle_t*)client, &fd);
    fprintf(stderr, "Worker %d: Accepted fd %d\n", getpid(), fd);
    uv_read_start((uv_stream_t*)client, alloc_buffer, echo_read);
  } else {
    uv_close((uv_handle_t*)client, NULL);
  }
}

int main() {
  loop = uv_default_loop();

  uv_pipe_init(loop, &queue, 1 /* ipc */);
  uv_pipe_open(&queue, 0);
  uv_read_start((uv_stream_t*)&queue, alloc_buffer, on_new_connection);
  return uv_run(loop, UV_RUN_DEFAULT);
}
